Budyko Energy Balance Model

Budyko (1969): Earth's temperature T balances incoming solar vs outgoing IR:
C·dT/dt = S(1-α(T))/4 − (A + BT) + F

Ice-albedo feedback: as T cools, ice expands → higher albedo α → less absorbed solar → more cooling. This is a positive feedback creating two stable states:
• Warm Earth (~15°C)
• Snowball Earth (~−50°C)

The bifurcation diagram shows how changing solar forcing triggers abrupt transitions. The Neoproterozoic snowball events (~700 Mya) may have been triggered this way.